Many conventional flow control systems for perfusion, transfusion, and infusion systems are provided by the use of a flow regulator in the form of a roller clamp attached to tubing leading from a drip chamber to the patient. Such roller clamps rely on deformation of the tubing to modify the fluid flow path in order to slow down or speed up the rate of flow to the patient. Over time, the stress induced in the tubing and creep effects gradually alter the resiliency and dimensions of the tubing, altering the flow rate as set by the health care provider using the roller clamp.
The effects of stress and creep are particularly profound when non-PVC tubing is used, such that roller clamps may be almost non-effective when used with non-PVC tubing. While PVC tubing is more resistant to such degradation and performs better with roller clamps than non-PVC tubing, some alteration is still present and thus a flow control system that does not allow unintended alteration of the flow rate through the tubing of perfusion, transfusion or infusion systems would be preferable.
Another drawback of using roller clamps is the difficulty in setting the flow rate of a liquid limited patient such as a neonatal patient. For such a patient, the ability to accurately set a low flow rate is very important. The tubing clamp is ill-suited for such setting as even a slight movement of the roller can lead to a more than desired change in the flow rate thereby leading to multiple slight movements of the roller to set such a rate. This prolongs the time needed to set the rate. In addition, even a slight creep over time caused by the roller clamp can result in a change in the flow rate bringing it outside the desired range. This leads to the necessity for the health care provider to frequently check and if needed adjust the flow rate back to the desired rate.
A further drawback of conventional flow control systems is the possibility of providing a closed loop fluid control to the flow control system. Roller clamps are configured to be manipulated by the health care provider and are problematic to incorporate into an automatic system which may manipulate the clamp in dependence on sensed parameters such as the monitored flow or condition of the patient.